Copolyester fibers and filaments having defined shrinking properties

ABSTRACT

FIBERS AND FILAMENTS HAVING DEFINITE DEGREES OF SHRINKAGE IN HOT OR BOILING WATER AND IN ATMOSPHERE OF A HOT GAS ARE PROVIDED. THE FIBERS AND FILAMENTS CONSIST OF POLYETHYLENE TEREPHTHALATE MOSIFIED WITH 2,2-DIMETHYL-PROPANEDIOL-1,3.

Jan. 29, 1974 BUTTNER ET AL 3,789,031

COPOLYESTER FIBERS AND FILAMENTS HAVING DEFINED SHRINKING PROPERTIES Filed Oct. 30, 1970 2 Sheets-Sheet 1 SHRINKAGE [v0 I TEMPERAJURE PC]- so so 100 INVEINITORS' GERT BUTTNER ADOLF HARTMANN PETER BRAUN United States Patent Filed Oct. 30, 1970, Ser. No. 85,646 Claims priority, application Germany, May 14, 1970, P 20 23 527.2 Int. Cl. C08g 17/100 US. Cl. 260-75 T Claims ABSTRACT OF THE DISCLOSURE Fibers and filaments having definite degrees of shrinkage in hot or boiling Water and in the atmosphere of a hot gas are provided. The fibers and filaments consist of polyethylene terephthalate modified with 2,2-dimethyl-propanediol-l ,3

The present invention relates to copolyester fibers and filaments having defined shrinking properties.

It has been proposed to produce yarns and textile fabrics from fibers and filaments having different shrinking properties. When shrinkage is brought about by a chemical or thermal treatment, the type of fibers or filaments having a higher degree of shrinkage causes the component with weak shrinkage or without shrinkage to form bends and crimps, whereby the yarn or fabric made therefrom develops a certain bulkiness which is highly appreciated for many applications.

The known polyester fibers, which have a considerably higher degree of shrinkage than normal fiber types (high shrinkage polyester fibers), exhibit a relatively high degree of shrinkage of over 20% in boiling water or they reach their full degree of shrinkage already at a temperature of about 100 C. Owing to the fact that the afiinity of polyester fibers for dispersion dyestuffs is insuflicient at low temperatures, the material must be dyed at the temperature of boiling water or even at still higher temperatures so that yarns and fabrics containing the aforesaid high shrinkage fibers in admixture with fibers of low shrinkage or without shrinkage cannot be rendered sufficiently bulky after dyeing at elevated temperature. It is, however, often desirable to add bulk to fabrics made of polyester fibers and filaments having difierent colors. Hence, polyester fiber materials are needed which do not shrink or shrink to a small extent only when being dyed and have a high degree of shrinkage at higher temperatures.

The present invention provides fibers and filaments of polyethylene terephthalate modified with 2,2 dimethylpropane-diol-1,3 and containing 1 to 20% by weight, preferably 3 to 7% by weight, calculated on the polyester, of dimethylpropylene units in the molecule, which fibers and filaments are characterized by a degree of shrinkage in hot or boiling water of at most 20% at the boil, preferably of at most 2% at the boil, and a degree of shrinkage in an atmosphere of a hot gas, advantageously hot air, in the range of from 20 to 60%, preferably to 45% and more preferably at 200 C.

The shrinkage behavior of the modified polyester fibers and filaments of the invention is illustrated in the accompanying drawing.

More particularly the modified polyester fibers and filaments of the invention are characterized by a degree of shrinkage in hot or boiling water as plotted on FIG. 1 which is not higher than the values of curve 1 (shrinkage at the boil of 20%) and a degree of shrinkage in an atmosphere of a hot gas, preferably hot air, as plotted on 3,789,031 Patented Jan. 29, I974 ice FIG. 2 which is in the range limited by curves 3 and 3' (shrinkage of 20 to 60% at 200 C.). More particularly, the modified polyester fibers and filaments of the invention are characterized by a degree of shrinkage in hot or boiling water which is not higher than the values of curve 2 in FIG. 1 (shrinkage at the boil of 2%) and a degree of shrinkage in an atmosphere of a hot gas which is in the range limited by curves 4 and 4' of FIG. 2 (shrinkage of 35-45% at 200 C.) and preferably corresponds to the optimum values represented by curve 5 of FIG. 2 (shrinkage of 40% in hot air of 200 C.).

In German Otfenlegungsschrift No. 1,495,625 it has been disclosed that fibers and filaments of polyethylene terephthalate which has been modified with 2,2-dimethylpropanedio1-1,3 and contains 1 to 20%, calculated on the polyester, of dimethyl-propylene units, has valuable high shrinkage properties. It is likewise known that after dyeing fiber materials of this type may again be shrunk by heating them at 180 C. It has not yet been proposed, however, to produce fibers and filaments from the aforesaid copolyesters which have the shrinking properties as defined by the curves of FIGS. 1 and 2, i.e. which do not shrink or shrink to a little extent only at the boil, but subsequently shrink to a considerable extent in an atmosphere of a hot gas. It is surprising that fibers and filaments having the aforesaid properties can be produced by a simple heat treatment of the drawn filaments of polyethylene terephthalate modified with 2,2-dimethyl-propanediol-1,3 as defined above, whereby the slope of the shrinkage/temperature curve is altered. For this purpose the drawn filaments are wetted with water or steam and dried at a temperature of from to 160 C. without allowing them to shrink. The dried filaments may additionally be heated without tension at a temperature of from to C. By this treatment the degree of shrinkage in boiling water can be strongly reduced whereas the degree of shrinkage, for example in hot air of to 210 C. is diminished to a slight extent only. To produce staple fibers having the defined shrinking properties the drawn tow is subjected to the heat treatment and then crimped and cut to staple fibers.

Referring to the drawings, the degree of shrinkage of the fibers and filaments is plotted on the ordinate in percent of the initial length prior to shrinking and the temperature of shrinkage is plotted on the abscissa in centigrades. With all measurements the shock shrink-age was determined, i.e. the shrinkage occurring when the fibers or filaments were immersed for 5 minutes in water having the respective temperature. The fibers and filaments according to the invention have a degree of shrinkage at the boil, i.e. at the temperature of boiling water, of at most 20% and preferably not higher than the values of curve 2 of FIG. 1. In spite of this relatively low degree of shrinkage at the boil of at most 20%, the fibers and filaments of the invention shrink to a considerable extent in an atmosphere of a hot gas, preferably hot air, in the range limited by curves 3 and 3' of FIG. 2. In FIG. 2 the shrinkage of the fibers or filaments is plotted in percent on the ordinate and the respective temperature of the hot air is plotted in centigrades on the abscissa. Shrinkage above 100" C. is brought about by suddenly placing the fibers and filaments in a zone of hot air heated at the respective temperature and having a heat capacity which is so high that after the introduction of the fibers and filaments the temperature is not reduced to a noticeable degree.

The fibers and filaments having the defined shrinking properties of the invention can be dyed at the boiling temperature of water in any desired shape, for example in the form of flock, tops or yarn, and made into a fabric together with other known fibers and filaments that have already been shrunk. Fibers and filaments of this type are,

13 besides polyester fibers other polyamide, polyacrylonitrile, or cellulose fibers. A fabric made in this manner can be rendered bulky by a treatment with hot air in which the fibers according to the invention shrink and cause the fibers that have already undergone shrinkage to form bends and crimps. It is especially favorable to effect the shrinking process in several steps, for example by drying the fabric at 140C. and thermosetting it at 180 190 C. When the fabric is dried a predensification takes place and the final densification is brought about during thermosetting. In this manner a fabric having an especially uniform and smooth aspect can be produced. When polyester high shrinkage fibers of unmodified polyethylene terephthalate are used, for example, the fabric has an undesired cracked aspect owing to the shock-like development of shrinkage. A further advantage of the polyester high shrinkage fibers of the invention resides in the fact that yarns containing the said fiber material can be steamed to set the twist in the preparatory operations to weaving without fear of a blocking of the shrinkage in the atmosphere of a hot gas. It should also be noted that the fibers made of or containing the modified polyesters of the invention have an improved dye receptivity, a pleasant handle and a very little tendency to pilling.

The following examples illustrate the invention:

Preparationof the tow 200 kilograms of a Copolyester of terephthalic acid, ethylene glycol and 2,Z-dimethyl-propanediol-1,3- containing of dimethyl-propylene units, calculated on the polyester, were dried and spun from the melt through a spinneret having 90 orifices each 0.5 mm. in diameter at a rate of 135 grams per minute at a draw-otf speed of 1400 meters per minute. 1,500 of the spun filaments were combined to form a tow which was drawn in steam in a ratio of 1:3.7. The tow was then treated as follows:

Example 1 The drawn tow was passed between two rolls having the same speed through a zone of air heated at 140 C. with a residence time of 3.5 seconds. The tow was crimped and cut. The fibers obtained had the following properties:

Tensile strength 32 p./d. tex.

Elongation at break 11 percent.

Shrinkage at the boil 20 percent.

Shrinkage in air of 200 C. 45 percent.

Example 2 The drawn tow was dried at 100 C. on heated drums, the residence time being 16 seconds, then crimped and cut. The fibers obtained had the following values:

Tensile strength 32 p./d. tex.

Elongation at break 22 percent.

Shrinkage at the boil 5 percent.

Shrinkage in .air of 200 C. 45 percent.

Example 3 The drawn tow was heated on heated drums of 80 C. with a residence time of 2 seconds and crimped. The crimped tow was then heated at 130 C. in a heated steam tube for 60 seconds and cut as usual. The fibers obtained had the following properties:

Tensile strength 29 p./d. tex.

Elongation at break 35 percent.

Shrinkage at the boil 1.5 percent.

Shrinkage in air of 200 C. 42 percent.

Example 4 The tow was dried as described in Example 2 and after drying the crimped tow was additionally heated for 60 seconds at 130 C. in a heated steam tube. The fibers obtained had the following properties:

4- Tensile strength 37 p./d. tex. Elongation at break 33 percent. Shrinkage at the boil 0.4 percent. Shrinkage in air of 200 C. 45 percent.

Since FIGS. 1 and 2 are drawn to scale the shrinkage values for particular temperatures may be readily determined for the particular curves 1-5. Thus as shown in FIG. 1 curve 1 might be defined as a smooth curve passing through the co-ordinate values of substantially 0% shrinkage at 40 C., 1.0% at 50 C., 2.7% at 60 C., 5.5% at 70C., 9.5% at C., 13.8% at C. and 20.00% at C. Curve 2 has the coordinate values of substantially 0% shrinkage at 40 C., 0.1% at 50 C., 0.3% at 60 C., 0.6% at 70 C., 0.9% at 80 C., 1.4% at 90 C., 2.2% at 100 C. In FIG. 2 curve 3 has the coordinate values of substantially 0% shrinkage at 80 C., 4.2% at 100 C., 11.0% at 120 C., 19.5% at 140 C., 29.0% at 160 C., 41.0% at 180 C., and 60.0% at 200 C. Curve 4 has the coordinate values of substantially 0% shrinkage at 90 C., 2.0% at 100 C., 7.1% at 120 C., 14.5% at 140 C., 22.5% at 160 C., 33.0% at 180 C., 45.0% at 200 C. Curve 5 has the coordinate values of substantially 0% shrinkage at 100 C., 4.5% at 120 C., 11.0% at 140 C., 19.0% at 160 C., 28.3% at 180 C., 40.0% at 200 C. Curve 4' has the coordinate values of substantially 0% shrinkage at C., 2.0% at C., 8.0% at 140C, 15.3% at 160 C., 24.5% at 180 C., 35.0% at 200 C. Curve 3 has the coordinate values of substantially 0% shrinkage at C., 1.5% at C., 7.0% at C., 12.0% at C., and 20.0% at 200 C.

What is claimed is:

1. Copolyester fibers and filaments of polyethylene terephthalate containing 1 to 20% by weight, calculated on the polyester, of 2,2-dimethylpropylene units, which fibers and filaments are characterized by a degree of shrinkage in hot or boiling water not higher than the values defined by a smooth curve passing through the coordinate values of substantially 0% shrinkage at 40 C., 0.1% at 50C., 0.3% at 60C., 0.6% at 70C., 0.9% at 80 C., 1.4% at 90 C. and 2.2% at 100 C., and a degree of shrinkage in the atmosphere of a hot gas within the range limited by a smooth curve passing through the coordinate values of substantially 0% shrinkage at 80 C., 4.2% at 100 C., 11.0% at 120 C., 19.5% at 140 C., 29.0% at 160 C., 41.0% at 180 C., and 60.0% at 200 C. and a smooth curve passing through the coordinate values of substantially 0% shrinkage at 130 C., 1.5% at 140 C., 7.0% at 160C., 12.0% at 180 C., and 20.0% at 200 C.

2. Copolyester fibers and filaments as claimed in claim 1, characterized by a degree of shrinkage in hot air within the range limited by a smooth curve passing through the coordinate values of substantially 0% shrinkage at 90 C., 2.0% at 100 C., 7.1% at 120 C., 14.5% at 140 C., 22.5% at 160 C., 33.0% at 180 C, 45.0% at 200 C. and a smooth curve passing through the coordinate values of substantially 0% shrinkage at 110 C., 2.0% at 120 C., 8.0% at 140 C., 15.3% at 160 C., 24.5% at 180 C., 35.0% at 200 C.

3. Copolyester fibers and filaments as claimed in claim 2 characterized by a degree of shrinkage in hot or boiling water which is not higher than the values defined by a smooth curve passing through the coordinate values of substantially 0% shrinkage at 40C., 0.1% at 50 C., 0.3% at 60 C., 0.6% at 70 C., 0.9% at 80 C., 1.4% at 90C., 2.2% at 100 C.

4 Copolyester fibers and filaments as claimed in claim 1, characterized by a degree of shrinkage in hot air corresponding to the values defined by a smooth curve passing through coordinate values of substantially 0% shrinkage at 100 C., 4.5% at 120 C., 11.0% at 140 C., 19.0% at 160 C., 28.3% at 180 C., 40.0% at 200 C 5. Copolyester fibers and filaments as claimed in claim 4, characterized by a degree of shrinkage in hot or boiling water which is not higher than the values definedby a 4 5 6 smooth curve passing through the coordinate values of 3,427,267 2/1969 Stieger et a1. 26075 R substantially 0% shrinkage a; 40C., 0.1% at 0., 3,461,199 8/1969 Campbell 264-346 0.3% at C., 0.6% at C., 0.9% at C., 1.4% 3,469,001 9/1969 Keefe 6--9 at C., 2.2% at C. 3,546,179 12/1970 Koller 26075 R References Cited 5 JAY H. WOO, Primary Examiner 3 091805 i /1 9:? 15 PATENTS 264290T usen ury 2,948,583 8/1960 Adams et a1 264210F 26075 290 3,407,112 10/1968 Karichoff et a1. 161165 10 

